According to entrenched conventional wisdom, the president enjoys considerable advantages over other litigants in the Supreme Court. Because of the central role of the presidency in the U.S. government, and the expertise and experience of the Solicitor General’s office, the president usually wins. However, a new analysis of the data reveals that the conventional wisdom is out of date. The historical dominance of the president in the Supreme Court reached its apex in the Reagan administration, which won nearly 80% of the cases, and has declined steadily since then. In the Obama administration, the presidency suffered its worst win rate, barely 50%. After documenting this trend, we discuss possible explanations. We find evidence that the trend may be due to growing self-assertion of the Court and the development of a specialized private Supreme Court bar. We find no evidence for two other possible explanations — that the trend is due to greater executive overreaching than in the past, or ideological disagreements between the Court and the presidency.